Railway signaling system



Dec. 10, 1929. A. E. HUDD 1,738,903

RAILWAY SIGNALING SYSTEM Filed Feb. 20, 1923 2 Sheets-Sheet l Dec.

10, 1929. A. E. HUDD RAILWAY SIGNALING SYSTEM Filed Feb. 20, 1923 2 Sheets-Sheet 2 Q. .l l $42 34 35 22 l A: i K /4 7 i w i 26 6 i 3 l i I kl a Patented Dec. 10, 1929 ALFRED ERNEST HUDD, OF NEW BRIGHTON, ENGLAND, ASSIGHOR, BY IEESI'IE AESItl-IJ- MENTS, T0 AUTOMATIC ELECTRIClNG, .0]? CHICAGO, ILLINUIE RAILWAY SIGNALING SYSTEM.

Application filed February 20,1923, Serial No...620,208, and in Great Britain February 21, 19522.

The present invention concerns improvements in and relating to railway signalling systems. The principal object of the invention is to provide an economical and highly reliable system of railway signalling in which transient.- currents are transmitted over the track prior to the admission of a train to a section, which transient currents are adepted to set up a short local track circuit at the end of the section, this local circuit remaining set up until the rails are short circuited by the passage of a train.

According to one teature of the present invention, the transient current trai'isinitted over the track is of a distinctive character such as a vibratory or alternating current of definite frequency, while the device which responds thereto is adapted to respond to current having the special characteristics chosen.

The use of alter ating or vibratory current of this character possesses the advantage not only that it prevents the false operation of the system due to stray current, but also that it enables the system to be used in connection with electric traction systems. Preferably an alternating current relay is provided for responding to the alternating or vibra tory currents thisrelay being broadly tuned to the frequency of the currents so that repeated adjustments are not required.

According to another feature of the present invention, track circuits are provided at each end of l main section arranged in such a manner that a previously energized device is de-energii ied when a train enters the section at either end, while a second device is adapted to be energized preparatory to lcausing a transient current to be automatically transmitted over the main section on the train leaving the section to bring about the energization of the first mentioned device.

Another feature of the invention is the provision of a device operated onthe passage of a vain which is adapted to cause a transient current to flow overa section of track automatically to test if the trackis clear; preterably this action takes place when the train has left the track.

A further feature of the invention is that short insulated sections of track located at each end of a main section are interconnected in such a manner that a train passing over either end section controls the operation of the same device or devices once a transient current has been transmitted over the track. The interconnection of the two sections can he conveniently carried out over a line wire running alongside the track.

till another feature ofthe present invention isan arrangementwhereby transient signals 111213 be transmitted over a much longer length ct track than has been possible hitherto without splitting up the track into insulated sections.

While the invention is generally applicable to any railway system and particularly to those in which long sections are required, this feature is of most value on electric systems operating on direct current with the track rails as a return. In such cases where the track is divided into insulated sections for signalling purposes, it is necessary to provide impedance bonds at the points of division in order that the power return may be uninterrupted. These impedance bonds may well fOllDtL serious item of expense and is the object of the invention to reduce their number to a minimum by the provision of relaying units which allow each insulated section to extend for the whole length of the block section without any intervening insu lation at the relaying units.

These and other features not specifically mentioned at this time will be better under stoodtrom the following description which treats by wayo'l' example with one embodiment of the invention. It will he understood, however, that considerable modifications may be made in the constructional details or the particular circuits WltllOlli) departing from the spirit of the invention.

The accompanying drawings comprislng Figuresl and 1 should be placed side by side with the corresponding portions in alignment and show a section of track equipped for a system of automatic transient track signalling oi? the simplest type, a relaying nnit being connected at an intermediate point C between A and B. Only one track is shown, but it is assumed that this is used for through traffic in the direction B to A only and that a similarly equipped track is used for traflic in the other direction.

The apparatus at A enclosed in the dotted rectangle could be located in the signal cabin or separately alongside the track since its operation is entirely automatic; the apparatus at B would preferably be located in the signal cabin, while the apparatus at C would be located alongside the track. To facilitate the understanding of the invention, the relaying unit at C will be ignored for the present and described separately after the general operation of the system has been dealtwith. One of the track rails is continuous while the other has at each end of the'section a short insulated portion which may be conveniently of one rail length; these portions are represented by 1 and 2. All the apparatus is shown in its normal position when the line is clear and ready for the passage of a train. Current is now flowing from battery 3, through relay 10, insulated rail 1, line wire 20, armature 33 and its front contact, and relay 16 to return. In this circuit relay 16 operates but relay 10 does not, thus the lever lock 18 (or a signal reverser) can obtain current from battery 9 by way ofv armature 31 and its front contact when the signahnan closes the catch handle contact 19. A circuit is alsonormally completed from battery 7 through protective resistance 22 to the return rail, relay 17, armature 30 and its front contact, insulated rail 2, armature 32 and its front contact back to battery. It will be noted that the circuit of each of the relays 16 and 17 is dependent on the other, so that if either becomes tie-energized, the other must also and it Will be necessary for an independent energizing circuit to be completed for them .to pick up and be maintained energized over the circuit described. I

Suppose now that the signal has been lowered and that a train advances into the section in the direction B to A. As soon as it reaches the insulated rail 2, relay 17 is short circuited by the wheels and consequently de-energizes, thereby opening its own'circuit at armature 32 and the circuit of relay 16 at armature 33.

' 27 is attracted and the vibrator 11 commences to oscillate with current from a tap off battery 5, vibrator -contacts 25, coil of vibrator 11, front contacts of armature 27, to return.

The train new passes clear of the insulated rail 2, whereupon the circuit of relay 10 is broken and its armature released. Current to the vibrator coil 11 is therefore cut oil. at the front contacts of armature 27 and during the period it takes the vibrator to come to rest, an alternating current from batteries a and 5 will flow to the track through back contacts of armature 27.

As the wheels of the train will be electrically connecting both the track rails together the alternating current impulses are simply short circuited. Since armatures 30 and 32 have left their contacts no current flows through any of the apparatus after the alternating current impulses have died away. This state of things continues till the train reaches insulated rail 1.

When this occurs, relay 10 is connected directly across battery 3 through the wheela of the train; consequently it is energiz d and attracts its armature 27. A circuit is thereby completed from tap of battery 5, interrupter contact 25, vibrator 11, and through armature 27 and its front contact to negative pole of battery 5 so that the vibrator starts operating.

vi hen the train is clear of the insulated rail 1, relay 10 is again de-energized; thereupon the circuit of the vibrator is opened at armature 27 but owing to its inertia it will continue to oscillate its armature for an appreciable time before coming to rest. .lmpulses of positive and negative current are therefore sent out alternately over the following circuit: from batteries -11; and 5, contacts 23 and 24, regulating resistance 21, over the portion of track between the insulated rails, to the transformer 12 and back via. the return rail and armature 27 and its back contact. If the track is clear, this alternating current will operate the alternating current relay 13 and cause it to oscillate its armature, thus making contacts 3a and 35 alternately. Circuits are thereby completed from battery 6 for the relays 14: and 15, and as these relays have non-inductive shunts across their windings and are provided with copper slugs as indicated by diagonal lines they are rendered slow to release and thus hold up as long as alternating current is fed to the relay 13. Relays 14 and 15, on attracting their armatures. complete the following circuit: from positive pole of battery 6, armature 2S, relay 16, relay 17, armature 29 to negative pole of battery. Consequently these relays energize and lock themselves energized through their contacts 30, 32 and 33 as before the train arrived. The apparatus is thus restored to the normal position in readiness for the next train to pass into the section.

Suppose now that a train backs into the section; as soon as it reaches the insulated rail 1, relay 16 will be shorted out and will de-energize, thus opening at armature 30 the circuit of relay 17, which will (lo-energize [ill messes also. Relay 10, however, will pick up with the results described above. When the train clears the insulated rail 1, the vibrator 11 will operate to connect alternatingcurrent to the track. As, however, the transformer 12 is short circuits-d by the train, this current is without etlect on the relay 13 and it will be impossible to release the lever lock 18 as long as the train is in the section. It will be noted that should a train come to rest in the section and clear of both insulated rails, no currentat all will flow through its wheels after the alternating current impulses have died away. Thus this system is particularly suitable for stations and other situations where trains may be standing for hours at a time. /Vith the ordinary arrangement of a track relay, battcry consumption is very heavy in such cases the battery practically short circuitcd for a long period.

It may be desirable to provide inthe signal cabin at A, a push or like key 26 for emergency use which will connect the insulated rail 1 with the return rail. this will have the same eii'ect as the presence of a train on rail 1, and relay 10 will be picked up, and on its release the track will be supplied with alternating current as in normal working.

The relaying unit shown at C on the drawing will now be described. In the present example it is responsive to alternating current only, and comprises a transformer 36, an alternating current relay 37, a pair of sluggish relays 38 and 39, a third sluggish L 5 relay l and an electromagnetically controlled vibrator 4:1. The alternating current relay 3'?" is preferably a polarized relay with a cen trally pivoted armature, broadly tuned to be more sensitive to current ofa particular frequency. i

The functions of the various parts will best be understood from a description of the operation in a specific case.

Eluppose that a transient current is transmitted over the rails: to the relaying unit; it will flow through the primary of the transformer 36 by way of armature l2 and its back contact. The alternating current relay 37 will thereupon be operated by the induced current in the secondary and will oscillate its armature thus making contacts a3 and all alternately. A circuit is thereby completed for the slow relays 38 and 39 which extends from positive pole of battery d through the relays, contacts 43 or a l, interrupter contact 46 of the vibrator ll to negative pole of battery. Since the contact 46 isclosed relays 38 and'39 will pick up and owing to their slow to release characteristic will remain energized as long as these conditions hold; they thus complete a circuit for the slow relay from battery 47 through contacts 48 and 4l9'. Relay a0 thereupon pulls up and closes its contacts a2 and 50. At contact 50, the circuit is completed from battery as for the vibrator 41 These two relaying units would then c and this therefore commences to oscillate its armature. This has the effect of connecting however, the circuit through the primary winding 01' the transformer 36 is opened and consequently relay 3'? receives no more current and its armature comes to rest. Relays 38 and 39 will therefore release a moment after and a little later still relay d0 releases also.

It might easily happen in practice that the succeeding relaying unit similar to the one illustrated would be sending out transient currents at this moment and that these currents coming back over the track would again operate the relaying unit under consideration. tinuc feeding each other with transient currents indctlnitelyand working of the system would become impossible.

This is prevented howeve since the encrgizing current i or the relays 38 and 39 has to pass through the interrupter contact it and since the vibrator does not come to rest at once this contact is still being operated at this time. The circuit for relays 38 and thus extends through the contacts 43 or ist of the relay 37 and through the interrupter contact 16, both of which are vibrating. Under these circumstances, the relays 38 and 39 do not energize, and by the time the vibrator comes to rest, the transient current will have been repeated to a suilicient {stance for itto be too weak to affect the relaying unit again.

It will thus be seen that a system of rail: way track signaling has been provided which is entirely automatic and in which, as the leakage path is restricted to the portion of track corresponding to the two insulated rails out of a total section length which may be very considerable, the battery consumption is negligibly small.

What I claim and desire to protectby Letters Patent is:--

1. A railway signalling system comprising a track, a source of electrical energy, vibrating means responsive to the :onnection and disconnection of said source of electrical energy to and from the rails of said track, switching means controlled by track conditions independently oihsaid vibrating means for effecting said connection and disconnection to operate said vibrating means and means controlled by said vibrating means to allow a train to enter said t 'ack it said track is clear.

2. A railway signalling system comprising a track, two batteries having their opposite poles adapted to be connected together and to one rail ct said track, a vibrating member adapted to connect the other poles ot said hatteries alternately to the other rail of said track and means connected across the rails of said track responsive to alternating current of a frequency equal to the frequency of the vibrating member and adapted to respond if the track is clear to allow a train to enter said track. 7

3 A railway signalling system comprising a track, two batteries having their opposite poles connected together and to one rail of said track, a vibrating member adapted to connect the other poles of said batteries alternately to the other rail of said track, a transformer having one winding connected across the rails of said track, a relay connected to the other winding of said transformer responsive to alternating current of the frequency of the vibrating member and adapted to respond if the track is clear to allow a train to enter said track.

4. A railway signalling system comprising a track, two batteries having their opposite poles adapted to be connected together and to one rail of said track, an electromagnet, a vibrating member adapted to be cont-rolled by said electromagnet to connect the other poles of said batteries alternately to the other rail of said track and means connected across the rails at the end of said track responsive to alternating current of a frequency equal to the frequency of the vibrating member and adapted to respond if the track is clear to allow a train to enter said track.

5. A railway signalling system comprising a track a source of electrical energy, vibrating means for momentarily rapidly connecting anddisconnecting said source of electrical energy to and from the rails of said track, an electromagnet adapted to cause said vibrating member to vibrate and means responsive to the connection'and disconnection of said source of electrical energy to take up an operative position if said track is clear to allow a train to enter said track.

' 6. In a railway signalling system, a track divided into two sections insulated'from each other, one constituting the main portion of said track and the other a short portion and located at one end of said main track, a source of electrical energy, switching means for connecting said source of electrical energy to saidlonger section to'cause a particular kind of current to be transmitted temporarily, a second source of electrical energy and means connected across said longer section adapted to respond to said particular kind of current to connect said secondsource of electrical energy to said shorter section so as to send a different kind of current over said short track if the longer section is clear.

7. In a railway signalling system, a track divided into two sections insulated from each other, one constituting the main portion of said track and the other a short portion and located at one s end of said main track, a source of electrical energy, switching means for connecting said source of electrical e11- ergy to said longer section to cause a particular kind of current to be transmited temporarily, a second source of electrical energy, means connected across said longer section adapted to respond to said particular kind of current to connect said second source of electrical energy to said shorter section so as to send a different kind of current over said short track if the longer section is clear, and locking means for maintaining said second kind of current flowing over said shorter section as long as the track is clear.

8. A railway signalling system comprising a track divided into two insulated sections, one constituting the main portion of said track and the other a short portion and located at one end of said main track, switcln ing means for causing alternating current to be transmitted temporarily over said longer section, means connected to the longer section and responsive to said alternating current to cause direct current to flow over said short track if the track is clear.

9. A railway signalling system comprising a track, means responsive only to electrical current of a distinctive character and means controlled independently of said responding means for causing current having said distinctive character to be only transitorily transmitted over said track to operate said responding means if said track is clear to allow a train to enter said track.

10. A railway signalling system comprising a track, a source of electrical energy, switching means for momentarily connecting and disconnecting said source of electrical energy to and from the rails of said track, a polarized relay having a weighted armature normally maintained in a neutral position by controlling springs or the like and adapted to respond to current of a frequency corresponding to the frequency of said connections and disconnections and a circuit adapted to be completed when said polarized relay is excited to allow a train to enter said track it said track is clear.

11. A railway signalling system comprising a track, means for causing an alternating current to be momentarily transmitted over said track, a polarized relay having a weighted armature normally maintained in a neutral position by controlling springs or the like and adapted to respond only to current of a frequency approximately equal to that of the alternating current which is caused to be transmitted over said track by said means and a circuit adapted to be completed by said relay to allow a train to enter said track if said track is clear.

12. railway signalling system comprising a track, a source of electrical energy, switching means for connecting and disconnecting said source of electrical energy to and from rails of said track, a polarized relay having a centrally pivoted armature normalif maintained in a neutral position by controlling springs or the like and contact'members adapted to be engaged by said pivoted armature after moving through a considerable are due to current of a definite frequency having persisted for a predetermined time, and a circuit adapted to be completed when said polarized relay is excited to allow a train to enter said track it said track is clear.

7 13. A. railway signalling system comprising a track, a source of electrical energy, vibratory means for rapidly connecting and disconnecting said source of electrical energy to and from the rails of said track, an electromagnetically controlled vibrating; member adapted to respond to the connections and disconnections of said source of electrical en ergy, two sluggish relays adapted to have their circuits completed alternately as the vibratory member successivelytalres up its two :rtreme positions and a circuit adapted to be controlled jointly by said two sluggish relays when energized to allow a train to enter said track it said track is clear.

let. A railway signalling system comprising a track, mean for causing an alternating current to be transitorily transmitted over said track, an electromagnetically controlled vibrating member adapted to respond to said alternating current, two sluggish relays adapted to have their circuits completed alternately as the vibrating member successively takes up its two extreme positions, a third sluggish relay controlled by said sluggish relays jointly and adapted to complete a circuit to allow a train to entersaid track if said traclr is clear.

15. A railway signalling system comprising a track, two batteries having their opposite poles adapted to be connected together and to one rail of said track, an elcctro-magnetically controlled vibrating member adapted to vibrate tor a predetermined time-on deenergization to connect the other poles of said batteries alternately to the other side ofsaid track, a transformer having one winding connected to said track, a polarized relay connected to the otherwinding of said transformer, and provided with a Weighted armature adjusted to respond to alternating currents oi? the frequency of the vibrating member, two sluggish relays having their circuits closed alternately by said armature when vibrating, a third sluggish relay controlled jointly by said two sluggish relays, a signal and controlling means for said signal influcncedrby said third sluggish relay according as to whether current transmitted over said track is enabled to operate said polarized relay or not.

16. An arrangement for relaying transient currents over acontinuous electrical conductor comprising a device responsive to said transient currents, at second device controlled by said first mentioned device to cause similar transientcurrents to' be relayed over the conductor, and means for automatically preventing said iirst mentioned device after having once operated from again operating effectively until after a predetermined time in response'to transient currents still traversing the conductor.

17; A railway signalling system compri ing a track, means for causing a transient currentto be transmitted over said track, a device connected across said track adapted to respondto a transient current, a second device controlled by said first mentioned device to cause a strengthened transient current to be transmitted over said track means forautomatical ly preventing said first mentioned device after havinwonce operated from again operating efiectivbly until after a predetermined time andmeansrresponsive to transient current transmitted:by=said seconddevice to permit the passage of a train over said track it the track is clear.

18. An arrangement for relaying transient currents over a continuous electrical conductor comprising an' eleetromagnet responsive to said transientcurrents;armatures adapted to operate contact memberswhen said electromagnet responds to cause a transientcurrent to be transmitted-over said conductor and means for preventing the armatures of said electromagnet being. again effective to cause antr'ansient current to be transmitted over said conductor for a distinct interval oi. time 19'. A railway signalling system compris ing a track, means for causing: a transient current to be transmitted: over said track, an electromagnet connected across said track and adapted to respond to a transient current, a contact member controlled by said electromagnet to cause a strengthened transient current tobe transmitted over said track and to control other contact members to open the circuit of said electromagnet to permit the electromagnet to release and means respo-ir give to transient currents transmitted through the agency of said'iirst contact member to permit the passage of a train over said track it thetrack is clear.

20.: A railway signalling system comprising a track, means for causing a transient current to=be transmitted over said track, an electromagnet connected 1 across said track adapted to respond to a transient current, a contact member controlled by said electromagnet to cause astrengthened transient current to betransmitted 'over said track, means for automatically rendering. the circuit con trolled by said a contact member ineifective for a predetermined time alter having once operated, and means responsive tothe transientcurrents firsttransmitted by said a con tact member to permit the passageof a train over said track if the track is clear. I

Anarrangement for relaying alternat ing or vibratoryicurrents over a continuous electrical conductor, comprising an electromagnetically controlled vibratory device responsive to said transient currents, a second vibratory device set in operation by said first of said second vibratory device. for a predetermined time in response to transient currents which may still be traversing the conductor. I r

22. An arrangement for relaying alternating or vibratory currents over a continuous H electrical conductor comprising an electromagnetically controlled vibrating device responsive to saidalternating or vibratory currents, a second electromagnetically controlled vibrating device controlled by said-first mentioneddevice to cause similar vibratorycurrents to be relayed over the conductor, and a contact making device controlled by said second vibratory device for rendering said first vibratory device ineffective to again cause the operation of said second device for a predeterminedtime in response to transient currents traversing the-conductor.

23. An arrangement for relaying alternating or vibratory currents over a continuous electrical conductor comprising an electromagnet connected to said electrical conductor and adapted to respond to said currents to cause its armature to vibrate, two sluggish relays adapted to be energized alternately when; said armature vibrates, a circuit controlled-jointly b said sluggish relays, adapted to effect t e opening of the connection' between said electromagnet and said conductor and an eleetromagnetically controlled vibrating device adapted to be energized'bysaid electromagnet to cause similar vibratory 'or alternating currents to be relayed over said conductor.

24; An arrangement for relaying transient currents over a continuous electrical conductor comprisingan electromagnet connected to said conductor and adapted to respond to alternating currents to cause its armature to vibrate,- two sluggish relays adapted to have their circuits closed alternately when said armature vibrates, a circuit controlled jointly "by saidtwo sluggish relays, anelectromagnetically controlled vibrating device included inthe circuitcontrolled by said two sluggish relays and adapted to cause similar vibratory or alternating currents-to be transmitted over said conduetor'when said two sluggish relays are jointly operated. and contacts adapted to be'eontrolled by the electromagnetically con- 1 trolled vibratory'member to rapidly open the circuitof said sluggish relays so as to cause their de-energization and maintain them deenergized for a predetermined time until the vibrations cease.

25. An arrangement for relaying alternating or vibratory currents over a continuous electrical conductor, comprising a polarized electromagnct connected to said conductor and adapted to respond to said currents to cause its armature to vibrate, two sluggish relays adapted to have their circuits completed alternately when said armature vibrates, a third sluggish relay adapted to have its circuit completed ointly by said two first mentioned sluggish relays, an electromagnetieally controlled vibrating device adapted to have its circuit completed by said third sluggish relay to disconnect said polarized electromagnet from said conductor, two batteries having their opposite poles connected together and to a common lead connected in circuit with said electrical conductor, the other poles of said batteries bein adapted to be connected alternately by said vibrating device to a lead connected by said third sluggish relay when operated to said electrical conductor, and contact members controlled by said vibrating device to open the circuit of Said two first mentioned sluggish relays so that they cannot be again energized until said vibrator has come to rest.

26. In a railway signaling system, a track, a source of electrical energy, a vibrating device adapted to connect and disconnect said source of electrical energy to and from the rails of said track, an electromagnet for controlling the operation of said device and circuit connections between said track, said source of electrical energy and said electromagnet arranged so that a circuit is completed by a passing train to cause said vibrating device to be transitorily operated.

27. A railway signalling system comprising a track having short insulated portions at each end of a main section, a normally energized device connected to said insulated sections, in such a manner as to be de-energized when a train enters the section at either end and a normally de-energized device adapted to be energized on the train leaving the section preparatory to causing a transient current to be automatically transmitted over the main section 01" said track to bring about the re-energization of said first mentioned device.

28. In a railway signalling system, a track, a device adapted to be controlled by a passing train to cause a transient current to flow over said track automatically, and switching meanslocated in a signal cabin and adapted to be operated to cause said device to effect the transmission of a transient current over the track.

29. In a railway signalling system, a track, and an electromagnetic device connected to said track adapted to be energized by the presence of a train on said track to cause a transient current to flow over said track an ton'iatically when the train leaves the track. 80. In a railway signalling system, a track, an electromagnetic device connected to said track adapted to be energized by the presence of a train on said track to cause a transient current to flow over said track automatically when the train leaves the track, and a switching device located in the signal cabin adapted to connect the rails of said track together to cause the energization of said electromagnetic device to cause a transient current to llow over said track independently of the w passage of a train.

81. in a railway signalling system a track, a source of electrical energy, means for rapidly connecting and disconnecting said source to and from the rails of said track, two

20 slow release relays, another relay responsive to said electrical energy to alternately complete circuits for said slow release relays to maintain them energized, and a control circuit adapted to be jointly controlled by said as slow relays.

32. A. railway signalling system comprising a traclr, means for causing a periodic current to be transitorily transmitted over said track, a vibratory member adapted to so respond to said current, two slow release relays having circuits completed alternately by said vibratory member and a third relay jointly controlled by said slow release relays.

83. in combination with a section of rail- 35 ny track, a first relay, a signal controlled by the first relay, a second relay, means for at times closing the second relay for a brief interval of time, a piclcup circuit for the first relay controlled by the second relay, and

so a stick circuit for the first relay.

in combination, a section of railway track, a first relay, a signal controlled by the iii-st relay, a second relay, a trackway device comprising a winding, means for at times 45 energizing the second relay if and only if the winding is intact, a pick-up circuit for the first relay controlled by the second relay, and a stick circuit for the first relay.

ln testimony whereof I affix my signature.

to iLFlRED ERNEST HUDD. 

